The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Casting is a manufacturing process used for making parts having complex shapes that would be otherwise difficult or uneconomical to make by other methods. With respect to internal combustion engines, casting is used for making many metal parts (“metal casting”). Metal casting includes introducing liquid metal (e.g., aluminum, iron, etc.) into a mold that includes a hollow cavity of a desired shape. The liquid metal is then cooled until the metal solidifies, and the solidified metal is taken out of the mold resulting in the desired part.
Metal casting, however, may suffer from defects such as porosity due to solidification shrinkage and gas partition from the liquid metal. Porosity refers to voids being formed within the metal part as it cools and solidifies. Porosity may increase the probability of the part breaking. Solidification shrinkage refers to uncompensated contraction of the metal as it solidifies, changing from a liquid to a less dense solid. Therefore, in order to fill out the mold cavity during solidification, typical molds include mold components such as gating, runners, and/or risers that are filled with reservoirs of liquid metal to compensate for solidification contraction.